For example, a light source such as, for example, a light emitting diode (LED) or a laser diode may be used in various lamps such as, for example, a vehicle lamp. These lamps may perform so-called temperature derating for controlling a drive current applied to the light source depending on a temperature, in order to protect the light source from heat under a high temperature.
For example, when the temperature of the LED is equal to or higher than a predetermined value, the value of a drive current to be supplied to the LED is lowered depending on the temperature.
Japanese Patent Laid-open Publication Nos. 2016-201341 and 2016-192512 disclose a vehicle lamp which performs temperature derating.